Carbonyls in the metropolitan area of Mexico City: calculation of the total photolytic rate constants Kp(s(-1)) and photolytic lifetime (tau) of ambient formaldehyde and acetaldehyde

A great number of studies on the ambient levels of formaldehyde and other carbonyls in the urban rural and maritime atmospheres have been published because of their chemical and toxicological characteristics, and adverse health effects. Due to their toxicological effects, it was considered necessary to measure these compounds at different sites in the metropolitan area of Mexico City, and to calculate the total rate of photolytic constants and the photolytic lifetime of formaldehyde and acetaldehyde. Four sites were chosen. Sampling was carried out at different seasons and atmospheric conditions. The results indicated that formaldehyde was the most abundant carbonyl, followed by acetone and acetaldehyde. Data sets obtained from the 4 sites were chosen to calculate the total rate of photolysis and the photolytic lifetime for formaldehyde and acetaldehyde. Maximum photolytic rate values were obtained at the maximum actinic fluxes, as was to be expected.     

人工快速渗滤系统对污染物的去除机制

人工快速渗滤系统(CRI)是在传统的污水快速渗滤处理系统(RI)的基础上发展起来的一种新型的污水土地处理技术.通过对CRI的模拟,揭示了非生物机制与生物机制对有机物、营养元素的降解机制.结果表明,CRI对污水中污染物的去除是在非生物机制与生物机制协同作用下完成的.对污水中的有机物和氮的降解以生物机制为主、非生物机制为辅;对磷的降解则以非生物机制为主、生物机制为辅.生物机制对有机物、氮的去除占70%以上,非生物机制对磷的去除占61.9%.系统中氮转化以硝化效果为主,反硝化效果较弱.     

Subsoil TPH and other petroleum fractions-contamination levels in an oil storage and distribution station in north-central Mexico

Many oil industry related sites have become contaminated due to the activities characteristic of this industry, such as oil exploration and production, refining, and petro-chemistry. In Mexico, reported hydrocarbon spills for the year 2000 amounted to 185 203, equivalent to 6252 tons (PEMEX, 2000). The first step for the remediation of these polluted sites is to assess the size and intensity of the oil contamination affecting the subsoil and groundwater, followed by a health risk assessment to establish clean up levels. The aim of this work was to characterize the soil and water in a north-central Mexico Oil Storage and Distribution Station (ODSS), in terms of TPHs, gasoline and diesel fractions, BTEX, PAHs, MTBE, and some metals. Besides, measurements of the explosivity index along the ODSS were made and we describe and discuss the risk health assessment analysis performed at the ODSS, as well as the recommendations arising from it. Considering soils with TPH concentrations higher than 2000 mg kg⁻¹, the contaminated areas corresponding to the railway zone is about 12 776.5 m², to the south of the storage tanks is about 6558 m², and to the south of the filling tanks is about 783 m². Total area to be treated is about 20 107 m² (volume of 20 107 m³), considering 1 m depth.     

Response to organic enrichment of infaunal macrobenthic communities under salmonid seacages

The response of infaunal macrobenthic communities beneath salmonid seacages to solid organic wastes (food pellets and fish excreta) was tested by means of the ABC-method (abundance, biomass comparison method: Warwick 1986) on samples collected from the SAFCOL seafarm at Badger Cove, southeast Tasmania, from February to July 1988. The intermittent nature of the addition of organic waste allowed us to monitor decline and recovery of the macrofauna, i.e., harvesting of a cage permitted a period of recovery whilst restocking precipitated a decline. The ABC-method proved to be a sensitive indicator of community health. Under a normal feeding regime the macrofaunal community structure indicated a moderately disturbed condition. Only 7 wk after the cage was harvested, species richness had increased markedly and the community adopted an undisturbed condition. Further improvement was apparent 14 wk post-harvest. Similarly, a decline to a moderately disturbed condition was apparent 7 wk after restocking and species richness had declined. No such changes occurred under a cage which contained fish continuously over the same period.     

Ecological compensation mechanism for urban green land and its application in Shanghai, China

Urban green land compensation plays an important role in county development, ecological environment management and many other fields. The concept, methods and principles of urban green land are introduced in this paper. According to the pay fee method, the value and ecological function of various types of urban green land were analyzed. The cost-benefit analysis method (CBAM) was used to estimate different external diseconomy benefits caused by green land loss. The authors applied CBAM to estimate such benefits in the case of Shanghai, China, and calculated the actual compensation value for green land. Results indicated that in 2002, the compensation value for the green land of Shanghai was RMB 8.58 × 10⁵ Yuan/hm².     

水环境中痕量重金属生物活性形态的分析

水环境中痕量重金属的生物活性形态,包括生物可吸收态和生物毒性形态,这种形态的分析是重金属形态分析研究的一个重要发展方向。对于水环境中重金属对生物的毒害现状评价、潜在危害预测以及水环境容量的确定、排放标准和污染治理方案的制定,具有重要意义。本文总结了各种物理化学法重金属形态分析的结果与生物测试重金属形态测定结果之间的相关性,进而探讨了应用物理化学方法进行金属生物活性形态分析的可行性和特点。     

土地利用规划环境影响评价——以双流县为例

土地利用规划对社会经济的发展和生态环境都会产生深刻的影响，尽早开展其环境影响评价对于保证决策的正确性是十分必要的。文章介绍了土地利用规划环境影响评价的基本程序和内容，提出了一系列的评价原则，分析了与其他环境影响评价的关系。并以双流县为例进行了分析。     

个旧锡矿成矿热液活动的微量元素地球化学指示

通过对不同地质体中微量元素含量对比及因子分析 ,明确成矿热液活动元素 ,区分不同地球化学类型的元素集群。研究表明 ,成矿热液活动源于花岗岩岩浆侵位 ,花岗岩浆期后热液及地下水在岩体热力驱动下构成了一个系统的矿化热液活动体系 ,对区内地层产生广泛的蚀变影响 ,形成矿体、热液活动脉体及矿化热液活动元素对围岩地层的改造。成矿热液活动体系为开放系统 ,运动方式以构造断裂导流为主 ,孔隙渗透为次。     

城市生活垃圾场垂直防渗技术应用与认识

为防止生活垃圾场渗滤液扩散 ,造成二次污染 ,本文着重论述了采用帷幕注浆进行垂直防渗的可行性 ,并结合工程实践 ,对生活垃圾场场址选择、帷幕注浆材料使用以及防渗工程布置作了分析和探讨。     

荧光光谱法鉴别海面溢油源的研究进展

本文以大量的研究成果介绍了荧光光谱技术在鉴别海面溢油源中的应用和进展。根据普通荧光光谱、同步扫描光谱、可变角同步扫描光谱和总荧光光谱等不同荧光光谱信息特等，论述了荧光光谱的三维特性及维特性及其在溢油鉴别中的应用。同时，结合低温荧光法、磷光光谱法、导数荧光光谱法等辅助方法和技术，介绍了国内外荧光光谱法鉴别海面溢油的新进展和新成果。